A method is known that comprises subjecting a sensitive laminate, wherein a peel layer comprising an organic polymer and a sensitive resin layer are located on a provisional substrate, to exposure and development so as to form an image on the peel layer and then transferring the image onto an arbitrary substrate. These methods are described, for example, in JP-B-46-15326 (the term "JP-B" as used herein means an "examined Japanese patent publication") and JP-B-49-441 (corresponding to U.S. Pat. No. 3,721,557). These methods are advantageous in that they are applicable not only to overlay type processes but also to surprint type processes such as for a color proof. However, they have some disadvantages in that it is required to use an adhesive upon each transfer, which makes the procedure troublesome, and in that the accuracy of site matching upon the transfer of each color is low.
In order to avoid the above-mentioned troublesome procedure, JP-A-47-41830 (the term "JP-A" as used herein means an "unexamined published Japanese patent application"), JP-A-48-93337 and JP-A-51-5101 each disclose a method wherein an image, which has been formed on an image-receiving sheet, is transferred by applying heat and pressure to the image-forming sheet. JP-A-51-5101, in particular, discloses a method comprising locating a hot-melt polymer layer as an adhesive on a permanent substrate, while JP- A-47-41830 discloses a method whereby an image is directly transferred to a permanent substrate such as art paper or coated paper.
However, these methods have the following disadvantages. One of these disadvantages resides in that the final image thus obtained is in the reverse of its original right and left. Further, the use of the hot-melt polymer having a high melting point elevates the transfer temperature. As a result, the dimensional stability of the substrate is lowered, which causes a deviation in the site matching of the transfer of each color. On the other hand, the use of a polymer having a low melting point frequently causes adhesion or scratches after the formation of an image. JP-A-59-97140 (corresponding to U.S. Pat. No. 4,482,625) discloses a method for improving over these disadvantages.
In this method, an image of each color is transferred once onto a provisional image-receiving sheet provided with a photopolymerizable receiving layer, and then, the image is retransferred onto the permanent substrate and subjected to overall exposure to thereby solidify the photopolymerizable image-receiving layer.
This method is highly effective in solving the above-mentioned problems. Namely, it makes it possible to provide a positive image of the mask original. Furthermore, since an ethylenically polyfunctional monomer is used in this method, the photopolymerizable image-receiving layer per se is soft at the transfer and makes it possible to conduct the transfer at a low temperature. Subsequently, the photopolymerizable receiving layer is solidified through exposure. Thus, the layer has a high resistance against adhesion and scarcely suffers from scratches.
JP-A-61-189535 (corresponding to U.S. Pat. No. 4,766,053) discloses an image-receiving sheet having a two-layer image-receiving layer comprising organic polymers located on a substrate. By using this image-receiving sheet upon the transfer of an image onto a permanent substrate, it may be arbitrarily selected either to transfer the second receiving layer onto the image layer or to transfer the image layer alone, by appropriately controlling the peeling between the receiving layers and that between the second layer and the image layer.
However, each of the above-mentioned methods, wherein the second image-receiving layer has a tackiness or a hot-adhesiveness which allows the hot adhesion thereof to the transferable image, has the following disadvantages.
(1) When the film surface of the transferable image sheet is located on the image-receiving surface of the image-receiving sheet and conducted to thermal transfer therewith, the tackiness of the image-receiving surface causes the incorporation of air-bubbles between the film surfaces, which are simply called hereinafter bubbles. As a result, the qualities of the image obtained are sometimes deteriorated.
(2) When an image is retransferred onto a permanent substrate, the second image-receiving layer has a thermal adhesiveness which remains on the image, which sometimes causes adhesion problems of the final products which are piled together and stored at a high temperature or a high humidity.